Method for forming fibre reinforced resin articles



April 5, 1966 LE ROY R. BoGGs 3,244,784

METHOD FOR FORMING FIBRE REINFORCED RESIN ARTICLES Original F'led Jan.l5, 1960 2 Sheets-Sheet 1 I 15.1. Naw Nhnn I April 5, 1966 LE ROY R.BoGGs 3,244,784

METHOD FOR FORMING FIBRE REINFORGED RESIN ARTICLES Original Filed Jan.15, 1960 2 Sheets-Sheet 2 ATTORNEKS United States Patent C) trespass 2Claims. (Si. 26d-137) This application is a continuation of my priorapplication, Serial No. 2,760, filed Ianuary 15, 1960, now abandoned.

This invention relates to the manufacture of article from fibrereinforced plastic or resin materials, and the invention is especiallyconcerned with the continuous, rather than intermittent or piecemealfabrication of elongated shapes or articles composed of fibrous orfabric. material imbedded ina resin or plastic. The invention isadaptable to the fabrication of a variety of shapes including strips,angles, bars, rods, channeled members, tubular members and many othershapes.

The advantage of various articles and structural pieces made of fibrereinforced plastic has been recognized, but generally speaking, theproduction of such reinforced plastic articles or shapes has heretoforebeen effected by discontinuous methods, such as molding. In a typicalknown operation, a mat of fibres, such as glass fibres are laid upon aform or within a mold, resin in liquid or semiliquid state is applied,and the article is then heat cured, usually under some pressure, forinstance by means of mating mold pieces.

Accordingr to the present invention an exceedingly simple method isprovided for the continuous production of a wide variety of shapes fromfibre reinforced plastic materials. In addition to rapidity and economyof production, the method and apparatus of the present invention havecertain additional important advantages, including the fact thatelongated pieces or articles of many different shapes may readily beformed, even including articles having reentrant grooves or channelstherein. Many such articles are ldiflicult if not impossible to produceby the known mating mold techniques.

In a typical operation according to the present invention, a wovenfabric strip formed of glass fibres is drawn through a liquid resinimpregnating bath and then through a confining channel in a formingdevice, the material being heated in the forming device and the rate offeed being such as to effect curing of the resin to the solid stageduring its passage through the forming device. Fibre reinforced plasticstrip may readily be fabricated in this way in a continuous manner, thestrip article being completed upon delivery from the forming Vdevice andbeing wound for example in a coil or, if desired, cut off to lengthsaccording to a specific use.

How the foregoing objects and advantages, as well as others which willoccur to those skilled in the art, are attained, will be clear from thefollowing description referring to the accompanying drawings whichillustrate a preferred embodiment of apparatus according to theinvention and which show a preferred embodiment of the method beingcarried out in said apparatus.

In the drawings:

FIGURE l is an elevational view, with certain parts in vertical section,showing a machine constructed according to the invention for thecontinuous manufacture of fibre reinforced resin strip, the sectionalparts of this view ICC being taken in the vertical plane indicated bythe line 1 1 on FIGURE 2;

FIGURE 2 is a plan view of a portion of the apparato shown in FIGURE 1,this view being on an enlarged scale and being taken as indicated by theline 2 2 on FIGURE 1, with certain parts shown in horizontal section andwith upper parts removed, for the sake of clarity;

FIGURE 3 is a transverse sectional view taken as indicated by thesection line 3 3 on FIGURE 1, this view being on an enlarged scale ascompared with the scales of both FIGURE 1 and FIGURE 2;

FIGURE 4 is a view on the scale of FIGURE 3 but taken as indicated bythe section line 4 4 on FIG- URE 1; and

FIGURE 5 is a view of the forming device shown in FIGURE 1, on asomewhat enlarged scale, and further illustrating certain heat transferpassages provided in the walls of the forming device.

Referring now to the drawings, the reference numerals 6 designate a mainframe or support structure for the apparatus. A plurality of spools 7are shown for supplying fibre reinforcing material, in the case shown,this material constituting woven Fiberglas strips F. The fabric stripsfrom these supply spools 7 are fed horizontally over a guide il andthence downwardly into an impregnating reservoir 9 adapted to contain asupply of a heat hardenable resin in liquid state, as indicated at 1li.The several fabric strips are passed over separated pairs of guides 1lprovided below the surface of the resin in the reservoir 9, in order toinsure thorough impregnation of each strip with the resin. The severalstrips are then drawn upwardly and out of the reservoir and into theentrance end of a forming device, upper and lower portions of which areindicated at 12 and I3. As best seen in FIGURES 4 and 5, the upper andlower parts of the forming device are shaped to provide a confiningchannel therebetween, through which the impregnated strips are drawn.Toward its entrance end, the confining channel in the forming device istapered to provide an enlarged inlet opening as is clearly shown at lidin FIGURE 5.

The main portion of the channel, i.e., beyond the tapered entranceportion, is preferably of substantially uniform cross section andpreferably also substantially straight to aid in forming a straight andaccurately dimensional piece.

Beyond the delivery end of the |channel in the forming device, lthereare arranged a plurality of pairs of friction rolls or rollers 15between which the completed strip is passed, and lby means of which thestrip lis drawn through the `forming device. Thus, these feed rolls atthe delivery end of Ithe apparatus serve to draw the reinforcing fibrousstrips 'from the `supply spools and also to draw those strips throughthe impregnating bath, as ywell as to draw the strip being formedthrough the forming device. The

- feed rolls l5 yare preferably driven yby means of a belt or chain suchas indicated at 17 which is actuated through one or more reductiongearing units 18, connected with a motor 19. Although live pairs ofdrawing or feeding rollers are illustrated, in most instances it "wouldnot be required to employ any such large number, as the force requiredfor drawing the formed strip through the forming device generally is notvery great. Indeed, in the case of a simple fiat strip, a forcesufficient to draw the strip through the forming device frnay -'beIapplied even t by direct hand pull, but for constancy of pull the useof feed rolls is preferred. Moreover, mechanisms other than rolls may beused for drawing out the formed article.

As shown in FIGURE 4 the forming device 122-13 is mounted by means of apair of channel members Eil which carry 'guides 21 working in guideslots yformed by means of brackets 22 mounted to the top flanges of themain frame channels 6. The lforming device is thus mounted `with freedomfor movement in -a direction generally parallel the direction `ofmovement of the strip being formed through the channel in the formingdevice. A gauge for measuring the pull being exerted on the strip (bythe feed rolls I5 -is indicated at 23, this gauge being connected bymeans olf a bracket 2.4i to the forming device and also to a fixedanchor point 25. In operation, the slide mounting of the forming device(as described just above with reference to FIGURE 4), together with thegauge 23, permits continuous direct reading of the pull required Kfordelivery of the strip through and from the forming device.

Although the apparatus has been illustrated and describe-d as positionedfor generally horizontal feed of the materials and the formed article,it will be understood that it may be differently arranged.

In general, it is preferred to employ heat settable or heat hardenableresin or plastic :materials having a liquid stage before curing and a`solid stage after curing. Thermosetting polyester laminating resins areeffectively used, for instance the resin identified P-43 as marketed byRohm and Haas Co. Such a resin is advantageously used with 4a smallquantity, for instance about '1% of a hardener, such as benzol peroxide.For such heat hardenable resin or plastic materials, the inventioncontemplates heating the forming device. While this may be done in avariety of ways, such as by electric heat-ing elements, it may be doneby circulation of a heat transfer medium through channels formed in theupper and lower parts 12 and I3 of the forming device, for instancechannels such as indicated at 26 in `FIGURE 5, having an inlet 27 and anoutlet 28. As the yforming device is preferably formed of metal, theheat applied tends to be conducted throughout the body of the formingdevice, and I have found that heating of the forming device throughoutthe entire length of the coniining channel has a tendency to cause theresin material to prematurely cure in the entrance end portions of thechannel and to stick or jam therein. With this in mind, I prefer toestablish a temperature gradient throughout the length of the confiningchannel, with the low end of the temperature scale toward the entranceend of the channel, yand with the high end of the temperature scaletoward the exit end of the channel. This is desirably accomplished byemployment of a heating means associated with the exit end por-tions ofthe forming device, while at the same time providing cooling meansassociated with the inlet end portions of the forming device. Thecool-ing means may take a ivariety of forms, but advantageously comprisechannels 29 for circulation o-f cooling liquid, for instance, water atordinary Water supply temperatures or, if desired, refrigerated, thecooling passages being provided with inlet Sil and an outlet 31 as shownin FIGURE 5.

VAlthough with cer-tain articles or shapes, all of the fibrous materialemployed may tbe impregnated prior to passage through the formingdevice, for many purposes it is desirable to Ifeed to the forming devicecertain fibrous material in unimpregnated condition. For example, thefeeding of strips such as indicated at S2 and 33 at opposite faces ofthe impregnated strips P improves the smoothness of operation `and tendsto minimize sticking in the forming device even though these stripsbecome saturated or impregnated by contact `with the impregnated stripsby the time they pass .part Way through the fonming device. The entirearticle therefore at the delivery end of the apparatus has a structurevwhich Iis sound or substantially yfree of porosity Ithroughout thecross section thereof, notwithstanding the fact that Icertain marginalor 'surface strips Iare initially `fed in unimpregnated condition.

The importance of employing unimpregnated strips or iibrous ymaterial atcertain surfaces of the article being lformed depends somewhat upon thecross sectional shape of the article. For example, in the case of apiece having angles or corners, resin material sometimes tends todeposit and accumulate in the corners and the feed of unimpregnatedfibrous material through those corners tends to sweep out particles ofresin tending to be deposited there. For this same purpose I have foundit to be desirable, in the case of formation of relatively thin str-ip,to feed yfibrous material, for example in the form of Fiberglas roving,in unimpregnated `form at the two edges 0f the strip.

This feed of impregnated and unimpregnated strip or other Ifibrousmaterial may be altered in various Ways, according to the shape of thearticle being formed.

It should further be under-stood that the form of the fibrous materialmay be varied. Indeed, the fibrous material may be fed in the `form ofWoven strip, as already mentioned above, or it may be Ifed in the formof Fiberglas mat. Still further, a multiplicity of threads or rovingsmay be fed, instead of one or more mats or strips. For certain purposes,`certain other types of fibrous material may be employed, -i.e., otherthan glass. Moreover, certain other materials or piece-s may be fedalong with the reinforcing libres, such as metal pieces, wood strips orthe like.

As above 'indicated the strip `or other article being formed may becontinuously delivered from the apparatus and may be wound in a coil, ormay be out off to desired lengths. In the latter event, and also for anyother purposes that may be desired, the feed o-f the materials and thearticle through the apparatus need not necessarily tbe completelycontinuous, but may be interrupted, at least tor intervals of time suchas required to cut off lengths of formed article, or to perform otherdesired operations `on the articles being produced. While for manypurposes it would be preferred to operate the apparatus continuously,Ivarious features of the invention -are also applicable Where the feedis interrupted or is intermittent, although it should Ibe noted thateven in such event, if desired, the method and apparatus maynevertheless be employed in the production of articles or pieces ofcontinuous or indefinite length. The Word continuous therefore is usedherein in a lbroad sense, although it is not intended Ito apply to suchoperations as the piecemeal tformation of articles by means of matingmolds which are `opened and closed for each operation.

It should still lfurther be understood that the number and arrangementof strips being fed will vary according to the cross section of thepiece tbe'ing formed, the shape of the forming device itself also vbeingvaried according to the shape of the piece desired.

The forming device des-irably has a smooth or polished surface, or maytbe coated with a material such as poly tetra-iluoroethylene, in orderto reduce sticking and facilitate drawing the piece through the formingdevice.

Attention is called to the fact that certain of the subject matterdisclosed in the present application is also disclosed and claimed in mycopending application Serial No. 115,633, filed .lune 8, 1961.

I claim:

I. In the formation of a fibre `reinforced resin article by feeding aheat hardenable liquid resin material and reinforcing libres through a:confining channel having a portion of substantial length and of uniformcross scctional shape conforming with the cross sectional shape of anarticle having an edge portion of considerable width as compared to itsthickness, the method which comprises impregnating with a heathardenable liquid resin material a fibrous reinforcement ystrip ofmatted glass frbers, feeding the impregnated strip through the confiningchannel in the portion thereof conforming -With said edge portion of thearticle longitudinally, feeding a brous roving through the confiningchannel in the portion thereof conforming with the extremity of saidedge portion and heating the resin to harden it while in confinement insaid 5 6 portion of the confining `channel of uniform cross sec-References Cited bythe Examiner tlonal ShaPe- UNITED STATES PATENTS 2. Amethod according `to claim 1 in which said fibrous roving fed into the`confining `channel is `am unimpregnated 2,8711911 2/1959 Goldsworthy etal- 156`441 roving and in which the Tesin impregnated strip carries 5 uSufcienlt resin material to saturate Said roving in said ROBERT F WHITEPrimary Examme" confining channel. I. A. FINLAYSON, Assistant Examiner.

1. IN THE FORMATION OF A FIBRE REINFORCED RESIN ARTICLE BY FEEDING AHEAT HARDENABLE LIQUID RESIN MATERIAL AND REINFORCING FIBRES THROUGH ACONFINING CHANNEL HAVING A PORTION OF SUBSTANTIAL LENGTH AND OF UNIFORMCROSS SECTIONAL SHAPE CONFORMING WITH THE CROSS SECTIONAL SHAPE OF ANARTICLE HAVING AN EDGE PORTION OF CONSIDERABLE WIDTH AS COMPARED TO ITSTHICKNESS, THE METHOD WHICH COMPRISES IMPREGNATING WITH A HEATHARDENABLE LIQUID RESIN MATERIAL A FIBROUS REINFORCEMENT STRIP OF MATTEDGLASS FIBERS, FEEDING THE IMPREGNATED STRIP THROUGH THE CONFININGCHANNEL IN THE PORTION THEREOF CONFORMING WITH SAID EDGE PORTION OF THEARTICLE LONGITUDINALLY, FEEDING A FIBROUS ROVING THROUGH THE CONFININGCHANNEL IN THE PORTION THEREOF CON-